Pregnenolone

What it is

At the start of all steroid hormones there is a single step: the enzyme CYP11A1 cleaves the side chain of cholesterol, and pregnenolone is formed. From it, via further enzymes, come progesterone, cortisol, aldosterone and, via CYP17A1 in two steps, also DHEA, the precursor of the sex hormones. That is why pregnenolone is often called the mother hormone in shops.

But pregnenolone is not just raw material. The brain makes it itself, and it acts there as a neurosteroid. Its storage form pregnenolone sulfate and its breakdown product allopregnanolone intervene directly in signal transmission between nerve cells. This very property is the reason clinical research has focused mainly on psychiatry and pain, not on hormone replacement.

How it is supposed to work

Research is following three leads. First: pregnenolone sulfate amplifies signals at NMDA receptors, which are central to learning and memory. Second: allopregnanolone amplifies the response of GABA-A receptors, the brain’s main braking system, and thereby has anxiety-relieving effects. Third, a French group showed in animals that THC increases pregnenolone production in the brain via the CB1 receptor, and pregnenolone then dampens several THC effects as a built-in brake.

Some of this has been measured in humans. People who swallow pregnenolone have higher blood levels of pregnenolone, allopregnanolone and pregnenolone sulfate. In a brain scan study, a single dose lowered the activity of the amygdala, the fear center, and strengthened its connection to the regulating prefrontal cortex, which went along with less anxiety. The cannabis lead has been taken so seriously that a separate drug was developed from it: the pregnenolone derivative AEF0117 reduced the pleasant effects of cannabis by 19 and 38 percent in a phase 2a study.

Where the memory reputation comes from

The reputation as a memory booster goes back to a 1992 mouse study. There, pregnenolone and pregnenolone sulfate improved retention of a learning task, and they were the most potent of all steroids tested, even in tiny amounts. The substances were, however, injected directly into the brain. Whether swallowed pregnenolone does the same in healthy people has not yet been tested by anyone in a controlled study.

What the studies show

Low back pain in veterans

Double-blind study with 94 analyzed veterans from the deployments in Iraq and Afghanistan. After one week of placebo, they received escalating doses of 100, 300 and 500 mg pregnenolone or placebo for 4 weeks. Pain intensity in the diary fell by 0.56 points more than under placebo, in retrospective rating by 0.70 points, and impairment at work and in daily life also improved. Pregnenolone was well tolerated.

The largest schizophrenia study

120 participants in Singapore, 8 weeks of pregnenolone or placebo in addition to usual treatment. The main goal, better cognition, was not achieved. Everyday functioning, on the other hand, improved, measured with a practical test, in 56 participants under pregnenolone versus 55 under placebo. Negative symptoms were already very low at baseline.

Bipolar depression

80 adults in a depressive phase of bipolar disorder received add-on pregnenolone, titrated up to 500 mg per day, or placebo for 12 weeks. Clinician ratings showed a significant course in favor of pregnenolone; for remission, only in self-report, with 61 versus 37 percent. The result is therefore encouraging, but not the same across all measurements.

Where the data stop

For the reasons most people buy pregnenolone, there are no human data. No controlled study has examined whether it improves memory, concentration, energy or hormone balance in healthy people, or influences aging. The studies come from psychiatry and pain medicine, are small, with 18 to 120 participants, and short, from a single dose to 12 weeks. In schizophrenia, a meta-analysis of 4 studies found no overall effect, a study in 82 women missed its main goal, and the largest study did not improve cognition. A striking feature is an inconsistent dose-response: in one study 30 mg per day worked, but 200 mg did not. In an autism study, irritability fell by 30.2 percent during just two weeks of placebo run-in, which shows how easily small studies can turn out false positive here. It is also unclear how much swallowed pregnenolone becomes DHEA, sex hormones or cortisol. A mini-study with 5 men found no change in urinary testosterone ratios after a single dose; systematic measurements with long-term intake are lacking. There are no long-term data.

Status, approval and legal

Pregnenolone is sold in German pharmacies and online as a dietary supplement. Whether this holds up legally has not been clarified. It is a steroid hormone precursor, and for its direct downstream product DHEA, the Joint Expert Commission of BVL and BfArM decided in 2025 that such products are medicines or unauthorized novel foods. There is no statement on pregnenolone itself, no entry in the EU Novel Food status catalogue and no prescription requirement in Germany. In the US, the FDA has described pregnenolone in warning letters as an unapproved drug. We therefore list it among the experimental substances and give doses only as study facts: the studies used 30 to 500 mg per day. In sport, pregnenolone is not on the World Anti-Doping Agency’s prohibited list; the 2026 list does not mention it.

Safety

In the controlled studies up to 500 mg per day and up to 12 weeks, pregnenolone was well tolerated; in an autism study, side effects were no more frequent than under placebo. Long-term data and systematic recording of side effects are lacking. Because the body can make DHEA and thus sex hormones from pregnenolone, caution is warranted in hormone-dependent conditions; there are no data on this, nor for pregnancy and breastfeeding. The US Anti-Doping Agency considers products that are supposed to supply or raise hormones to be particularly risky in principle, also because of fluctuating product quality. Almost all studies ran as an add-on to psychiatric medication, but interactions were not specifically studied. Anyone who takes medication or has a psychiatric or hormonal condition should therefore discuss pregnenolone with a physician beforehand.

Sources

• Naylor et al., JAMA Netw Open 2020 – low back pain in veterans, RCT
• Marx et al., Psychopharmacology 2014 – schizophrenia, 120 participants
• Ritsner et al., Psychiatry Clin Neurosci 2014 – negative symptoms in recent-onset schizophrenia
• Brown et al., Neuropsychopharmacology 2014 – bipolar depression
• Heringa et al., Schizophr Res 2015 – meta-analysis of hormonal add-on therapies
• Sripada et al., Biol Psychiatry 2013 – allopregnanolone and emotion regulation in fMRI
• Vallée et al., Science 2014 – pregnenolone as a brake on the CB1 receptor in animals
• Flood et al., Proc Natl Acad Sci USA 1992 – memory effects in mice
• Joint Expert Commission BVL/BfArM 2025 – classification of DHEA
• USADA – Pregnenolone: What You Need to Know